The use of enzymes derived from microbial cells to effect specific chemical transformations is well known. The free cells can be used efficiently in a batch-type process but do not lend themselves to continuous, industrial scale processes. This difficulty has led to an increased interest in the preparation of various forms of immobilized enzymes.
U.S. Pat. No. 3,779,869 (issued Dec. 18, 1973) discloses the stabilization of glucose isomerase activity by treating whole bacterial cells with glutaraldehyde. U.S. Pat. No. 4,060,456 (issued Nov. 29, 1977) involves the stabilization of microbial cell material having glucose isomerase activity by treating it with a cationic, polyelectrolyte flocculating agent such as a polyethylenimine or polyvinylpyrrolidone. The use of polyelectrolytes such as polyamines and cationic, polyacrylamides in the stabilization of microbial cells having active enzymes associated therewith is disclosed in U.S. Pat. No. 3,989,596 (issued Nov. 2, 1976).
Ono et al describe the immobilization of naringinase from Aspergillus niger by adsorbing the enzyme to tannin-aminohexyl cellulose prepared by the reaction of aminohexyl cellulose and cyanogen bromide activated Chinese gallotannin in Agric. Biol. Chem., 42(10), 1847-1853 (1978). Ohba et al disclose in Biotechnology and Bioengineering, Vol. XX, Pp. 665-676 (1978) that pullulanase can be successfully immobilized by the addition of tannic acid to the culture filtrate of thermophilic Streptomyces flavochromogenes to form a tannin-pullulanase adduct which can then be bound to TEAE-cellulose.
There is disclosed in U.S. Pat. No. 4,212,943 (issued July 15, 1980) a bacterial cell aggregate having increased particle hardness which is produced by contacting a mass of bacterial cells with a cross-linked reaction product of glutaraldehyde or cyanuric halide and a cationic polymer obtained by polymerization of an epihalohydrin and an alkylenepolyamine. Copending application Ser. No. 214,218 filed Dec. 8, 1980, now U.S. Pat. No. 4,337,313 discloses the immobilization of biocatalysts, including whole cells of the species Protaminobacter rubrum, by treatment with tannin and an adduct of glutaraldehyde and an epihalohydrin/polyamine copolymer.
The biocatalytic conversion of sucrose to palatinose is known. Hydrogenation of palatinose provides Palatinit, a noncaloric sweetener. The biocatalytic conversion can be accomplished by contacting viable cells of Protaminobacter rubrum containing sucrose-mutase activity with a sucrose containing medium. This conversion is carried out in a batchtype process, the economics of which would be improved by the immobilization of the biocatalyst to form particles possessing physical characteristics which would render it suitable for use in a packed-bed reactor in which the particles retain their biocatalytic activity during a continuous flow conversion of sucrose to palatinose.